Numerous studies have demonstrated changes in the activity of alcohol dehydrogenase (ADH), its isoenzymes and aldehyde dehydrogenase (ALDH) in the blood serum of patients with various liver diseases, including hepatitis C, liver tumors, fatty liver disease, and AIH (Chrostek and Szmitkowski 2000; Jelski et al. 2008, 2017, 2018a, 2018b). This evidence concerns the gene AVP and hepatitis C virus infection.